1. Field of the Invention
The present invention relates to thermal masking and decoy technologies, and more particularly to the holographic projection of a grey-scale image in the infrared spectrum that is related to the thermal signature of an object. The holographic projection forms a decoy that approximates the thermal signature of the object or forms a mask that obscures the thermal signature of the object.
2. Description of the Related Art
In warfighting systems, infrared (IR) sensors are deployed to detect the thermal signature of an object such as a person, airplane, tank, jeep etc. and generate an IR image. The system or its human operator may utilize the JR image to detect a “friend or foe”, identify the object or to target the object with a munition. Smart munitions may use IR sensors to acquire, track and finally destroy the object.
IR countermeasures may be deployed to create thermal decoys to confuse the warfighting system. In many cases the IR countermeasures only need to confuse the warfighting system for a brief period, perhaps as little as a few seconds, to achieve success. A missile locked onto a target may divert to prosecute the countermeasures. Once the missile has determined the countermeasures are not a valid target it may be too late to reengage.
U.S. Pat. No. 6,055,909 entitled “Electronically configurable towed decoy for dispensing infrared emitting flares” discloses a towed decoy having a payload that consists of foils and/or foil packs of a pyrophoric material. This material creates an IR signature behind the decoy that is more attractive than the infrared plume emitted by the aircraft engine. The fact that the JR decoy is towed insures that it will be kinematically correct by flying the same profile as the aircraft so as to remain within the field of view of the missile's seeker. Because the pyrophoric material can be metered (dispensed at varying and controllable rates) its radiant intensity can be matched with that of the engine of the towing aircraft. As the burn characteristics of the selected pyrophoric material match the burn profile of hydrocarbon based jet fuels, the towed IR decoy also emits a plume that spectrally matches that of its host aircraft's engine.
U.S. Pat. No. 8,066,218 entitled “Anti-missile defense suite” discloses an IR decoy that is deployed from an aircraft during or just after takeoff to provide a signature for any incoming missile. The IR decoy provides a heat source that has a higher radiant intensity than the hottest heat source on the engine. The towed IR decoy is powered by a laser source located within the aircraft and amplified to produce an IR decoy infrared signature in more than one spectral band of a magnitude greater than the infrared signature of said aircraft. The IR decoy infrared signature is distributed through a plurality of optical fibers of various lengths coupled to a plurality of small apertures within the IR decoy.
U.S. Pat. No. 8,339,580 entitled “Sensor-guided threat countermeasure system” discloses a countermeasure system for use by a target to protect against an incoming sensor-guided threat. The system includes a laser system for producing a broadband beam and means for directing the broadband beam from the target to the threat to blind or confuse the incoming sensor-guided threat.
BAE Systems has developed an active camouflage technology to protect military vehicles from detection by near IR night vision devices. The active camouflage consists of an array of hexagonal plates that can be rapidly heated and cooled to form any desired image, such as of the natural background or of a non-target object.